How not to show the label box of an input field ?

Hello All,

I'm trying to create a login form where the input field have no labels(the actual label is in the input field using the placeHolder). I tried setting the labels to null and the label width to 0 but I always end up with a small empty label box before the input field... Is there a way to get rid of the label (and it's surrounding box) before input fields?